Medical abortion regimen

Medical abortion is achieved by a combination of mifepristone and misoprostol, available as a composite pack (mifepristone and misoprostol [MS-2 Step]). Pharmacists may not always carry stock, so it is recommended that prescribers are aware of, or contact, local pharmacists when prescribing.

Mifepristone blocks the action of progesterone, the hormone necessary for a continuing pregnancy. It also softens and dilates the cervix, and increases uterine activity (by increasing prostaglandin concentrations and uterine sensitivity to prostaglandins).

Misoprostol is a synthetic prostaglandin E1 analogue that increases uterine contractility and softens the cervix. Both effects are enhanced by giving a preceding dose of mifepristone. Misoprostol is given buccally; oral dosing is less effective and causes more gastrointestinal adverse effects (eg nausea and vomiting).

To induce medical abortion, use:

If vomiting occurs within 1 hour of mifepristone administration, provide a repeat prescription for mifepristone and misoprostol, with an antiemetic administered beforehand.

In 5% of individuals, products of conception may be expelled in the time between taking mifepristone and misoprostol. Misoprostol should be taken regardless of bleeding or produce expulsion to minimise the risk of retained products of conception.

Normal activities can continue between taking mifepristone and misoprostol, but the individual will need to be at home, resting, with access to a toilet on the day misoprostol is taken. They may need an additional 1 to 2 days off work (depending on timing of the abortion and symptoms). A support person is recommended to be with the individual from the time misoprostol is taken until the heaviest bleeding has settled, to help access emergency treatment if required. For 14 days after taking mifepristone, the individual needs to be within 2 hours travel time of hospital emergency services, in case of haemorrhage or other complications.

Shorter dosing intervals (24 to 36 hours between taking mifepristone and misoprostol) can be used but are not licensed by the Australian Therapeutic Goods Administration (TGA). A shorter interval can be considered for practical reasons (eg to allow the timing of the bleeding to occur when a support person is available). However, limited data suggest that a 24-hour interval may slightly increase the risk of retained products of conception, particularly for gestations of 50 to 63 days.